Création des Logiciels de gestion d'Entreprise, Création et référencement des sites web, Réseaux et Maintenance, Conception
Création des Logiciels de gestion d'Entreprise, Création et référencement des sites web, Réseaux et Maintenance, Conception
We’re pleased to introduce the Google Webmaster Team as contributors to the Webmaster Central Blog. As the team responsible for tens of thousands of Google’s informational web pages, they’re here to offer tips and advice based on their experiences as hands-on webmasters.
Back in the 1990s, anyone who maintained a website called themselves a “webmaster” regardless of whether they were a designer, developer, author, system administrator, or someone who had just stumbled across GeoCities and created their first web page. As the technologies changed over the years, so did the roles and skills of those managing websites.
Around 20 years after the word was first used, we still refer to ourselves as the Google Webmaster Team because it’s the only term that really covers the wide variety of roles that we have on our team. Although most of us have solid knowledge of HTML, CSS, JavaScript and other web technologies, we also have specialists in design, development, user experience, information architecture, system administration, and project management.
In contrast to the Google Webmaster Central Team—which mainly focuses on helping webmasters outside of Google understand web search and how things like crawling and indexing affect their sites—our team is responsible for designing, implementing, optimizing and maintaining Google’s corporate pages, informational product pages, landing pages for marketing campaigns, and our error page. Our team also develops internal tools to increase our productivity and help to maintain the thousands of HTML pages that we own.
We’re working hard to follow, challenge and evolve best practices and web standards to ensure that all our new pages are produced to the highest quality and provide the best user experience, and we’re constantly evaluating and updating our legacy pages to ensure their deprecated HTML isn’t just left to rot.
We want to share our work and experiences with other webmasters, so we recently launched our @GoogleWebTeam account on Twitter to keep our followers updated on the latest news about our projects, web standards, and anything else which may be of interest to other webmasters, web designers and web developers. We’ll be posting here on the Webmaster Central Blog when we want to share anything longer than 140 characters.
Before we share more details about our processes and experiences, please let us know if there’s anything you’d like us to specifically cover by leaving a comment here or by tweeting @GoogleWebTeam.
Posted by Tony Ruscoe, Google Webmaster Team
this is a topic published in 2013... to get contents for your blog or your forum, just contact me at: devnasser@gmail.comGoogle BigQuery is designed to make it easy to analyze large amounts of data quickly. Today we announced several updates that give BigQuery the ability to handle arbitrarily large result sets, use window functions for advanced analytics, and cache query results. You are also getting new UI features, larger interactive quotas, and a new convenient tiered pricing scheme. In this post we'll dig further into the technical details of these new features.
BigQuery is able to process terabytes of data, but until today BigQuery could only output up to 128 MB of compressed data per query. Many of you asked for more and from now on BigQuery will be able to output results as large as the largest tables our customers have ever had.
To get this benefit, you should enable the new "--allow_large_results
" flag when issuing a query job, and specify a destination table. All results will be saved to the new specified table (or appended, if the table exists). In the updated web UI these options can be found under the new "Enable Options" menu.
With this feature, you can run big transformations on your tables, plus get big subsets of data to further analyze from the new table.
BigQuery's power is in the ability to interactively run aggregate queries over terabytes of data, but sometimes counts and averages are not enough. That's why BigQuery also lets you calculate quantiles, variance and standard deviation, as well as other advanced functions.
To make BigQuery even more powerful, today we are adding support for window functions (also known as "analytical functions") for ranking, percentiles, and relative row navigation. These new functions give you different ways to rank results, explore distributions and percentiles, and traverse results without the need for a self join.
To introduce these functions with an advanced example, let's use the dataset we collected from the Data Sensing Lab at Google I/O. With the percentile_cont()
function it's easy to get the median temperature over each room:
SELECT percentile_cont(0.5) OVER (PARTITION BY room ORDER BY data) AS median, room
FROM [io_sensor_data.moscone_io13]
WHERE sensortype='temperature'
In this example, each original data row shows the median temperature for each room. To visualize it better, it's a good idea to group all results by room with an outer query:
SELECT MAX(median) AS median, room FROM (
SELECT percentile_cont(0.5) OVER (PARTITION BY room ORDER BY data) AS median, room
FROM [io_sensor_data.moscone_io13]
WHERE sensortype='temperature'
)
GROUP BY room
We can add an additional outer query, to rank the rooms according to which one had the coldest median temperature. We'll use one of the new ranking window functions, dense_rank()
:
SELECT DENSE_RANK() OVER (ORDER BY median) rank, median, room FROM (
SELECT MAX(median) AS median, room FROM (
SELECT percentile_cont(0.5) OVER (PARTITION BY room ORDER BY data) AS median, room
FROM [io_sensor_data.moscone_io13]
WHERE sensortype='temperature'
)
GROUP BY room
)
We've updated the documentation with descriptions and examples for each of the new window functions. Note that they require the OVER()
clause, with an optional PARTITION BY
and sometimes required ORDER BY
arguments. ORDER BY
tells the window function what criteria to use to rank items, while PARTITION BY
allows you to define multiple groups to be analyzed independently of each other.
The window functions don't work with the big GROUP EACH BY
and JOIN EACH BY
operators, but they do work with the traditional GROUP BY
and JOIN BY
. As a reminder, we announced GROUP EACH BY
and JOIN EACH BY
last March, to allow large join and group operations.
BigQuery now remembers values that you've previously computed, saving you time and the cost of recalculating the query. To maintain privacy, queries are cached on a per-user basis. Cached results are only returned for tables that haven't changed since the last query, or for queries that are not dependent on non-deterministic parameters (such as the current time). Reading cached results is free, but each query still counts against the max number of queries per day quota. Query results are kept cached for 24 hours, on a best effort basis. You can disable query caching with the new flag --use_cache
in bq, or "useQueryCache
" in the API. This feature is also accessible with the new query options on the BigQuery Web UI.
The BigQuery UI gets even better: You'll get instant information while writing a query if its syntax is valid. If the syntax is not valid, you'll know where the error is. If the syntax is valid, the UI will inform you how much the query would cost to run. This feature is also available with the bq tool and API, using the --dry_run
flag.
An additional improvement: When running queries on the UI, previously you had to wait until its completion before starting another one. Now you have the option to abandon it, to start working on the next iteration of the query without waiting for the abandoned one.
Starting in July, BigQuery pricing becomes more affordable for everyone: Data storage costs are going from $0.12/GB/month to $0.08/GB/month. And if you are a high-volume user, you'll soon be able to opt-in for tiered query pricing, for even better value.
To support larger workloads we're doubling interactive query quotas for all users, from 200GB + 1 concurrent query, to 400 GB of concurrent queries + 2 additional queries of unlimited size.
These updates make BigQuery a faster, smarter, and even more affordable solution for ad hoc analysis of extremely large datasets. We expect they'll help to scale your projects, and we hope you'll share your use cases with us on Google+.
The BigQuery UI features a collection of public datasets for you to use when trying out these new features. To get started, visit our sign-up page and Quick Start guide. You should take a look at our API docs, and ask questions about BigQuery development on Stack Overflow. Finally, don't forget to give us feedback and join the discussion on our Cloud Platform Developers Google+ page.